ISO 7121:2006
(Main)Steel ball valves for general-purpose industrial applications
Steel ball valves for general-purpose industrial applications
ISO 7121:2006 specifies the requirements for a series of steel ball valves suitable for general-purpose industrial applications. It covers valves of the nominal sizes DN 8, 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 150, 200, 250, 300, 350, 400, 450, 500 (NPS 1/4, 3/8, 1/2, 3/4, 1, 1 1/4, 1 1/2, 2, 2 1/2, 3, 4, 6, 8, 10, 12, 14, 16, 18 and 20), and is applicable to pressure designations Class 150, 300, 600, 900, and PN 10, 16, 25, 40, 63, 100.
Robinets en acier à tournant sphérique pour les applications industrielles générales
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 7121
Second edition
2006-05-15
Steel ball valves for general-purpose
industrial applications
Robinets en acier à tournant sphérique pour les applications
industrielles générales
Reference number
ISO 7121:2006(E)
©
ISO 2006
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ISO 7121:2006(E)
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ISO 7121:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Pressure/temperature ratings.3
4.1 Valve rating.3
4.2 Shell rating .3
4.3 Seat and seal rating.3
5 Design .4
5.1 Flow passageway.4
5.2 Body .5
6 Materials .13
6.1 Shell .13
6.2 Shell material repair .13
6.3 Trim .14
6.4 Identification plate .14
6.5 Bolting.14
6.6 Seals.14
6.7 Threaded plugs .14
7 Marking .14
7.1 Legibility .14
7.2 Body marking.14
7.3 Ring joint marking .15
7.4 Identification plate .15
7.5 Special marking for unidirectional valves.15
8 Testing and inspection.15
8.1 Pressure tests .15
8.2 Inspection .17
8.3 Examination.18
8.4 Supplementary examination.18
9 Preparation for despatch .18
Annex A (informative) Information to be specified by purchaser .19
Annex B (informative) Identification of valve parts .20
Bibliography .23
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ISO 7121:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7121 was prepared by Technical Committee ISO/TC 153, Valves, Subcommittee SC 1, Design,
manufacture, marking and testing.
This second edition cancels and replaces the first edition (ISO 7121:1986), which has been technically
revised.
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ISO 7121:2006(E)
Introduction
The purpose of this International Standard is the establishment, in ISO format, of basic requirements and
practices for flanged, butt-welding, socket welding and threaded-end steel ball valves having flow
passageways identified as full bore, reduced bore and double reduced bore, suitable for general purpose
applications. Flanged end Class designated valves have flanges in accordance with ASME B16.5. Flanged
end PN designated valves have flanges in accordance with EN 1092-1. Valves with ends that are threaded
can have threads to either ISO 7-1 or ASME B1.20.1.
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INTERNATIONAL STANDARD ISO 7121:2006(E)
Steel ball valves for general-purpose industrial applications
1 Scope
This International Standard specifies the requirements for a series of steel ball valves suitable for general-
purpose industrial applications.
It covers valves of the nominal sizes (see ISO 6708 and ASME B16.34)
⎯ DN 8, 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 150, 200, 250, 300, 350, 400, 450, 500 (NPS 1/4, 3/8, 1/2,
3/4, 1, 11/4, 11/2, 2, 21/2, 3, 4, 6, 8, 10, 12, 14, 16, 18 and 20),
and is applicable to the following pressure designations (see ISO 7268 or EN 1333, and ASME B16.34):
⎯ Class 150; 300; 600; 900 and PN 10; 16; 25; 40; 63; 100.
1)
It includes provisions for valve characteristics as follows :
⎯ flanged and butt-welded ends in sizes 15 u DN u 500 (1/2 u NPS u 20);
⎯ socket welding ends in sizes 8 u DN u 100 (1/4 u NPS u 4);
⎯ threaded ends in sizes 8 u DN u 50 (1/4 u NPS u 2);
⎯ body seat openings designated as full bore, reduced bore, and double reduced bore;
⎯ materials;
⎯ testing and inspection.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 7-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances
and designation
ISO 7-2, Pipe threads where pressure-tight joints are made on the threads — Part 2: Verification by means of
limit gauges
ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions,
tolerances and designation
1) Valve characteristics are not necessarily available in all nominal sizes for all pressure designations, e.g. Class 900
applies only for reduced bore body seat openings.
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ISO 7121:2006(E)
ISO 228-2, Pipe threads where pressure-tight joints are not made on the threads — Part 2: Verification by
means of limit gauges
ISO 261, ISO general purpose metric screw threads — General plan
ISO 965-2:1998, ISO general purpose metric screw threads — Tolerances — Part 2: Limits of sizes for
general purpose external and internal screw threads — Medium quality
ISO 4032, Hexagon nuts, style 1 — Product grades A and B
ISO 4033, Hexagon nuts, style 2 — Product grades A and B
ISO 4034, Hexagon nuts — Product grade C
ISO 5208, Industrial valves — Pressure testing of valves
ISO 5209, General purpose industrial valves — Marking
ISO 5752:1982, Metal valves for use in flanged pipe systems — Face-to-face and centre-to-face dimensions
ISO 10497, Testing of valves — Fire type-testing requirements
EN 1092-1, Flanges and their joints — Circular flanges for pipes, valves, fittings and accessories,
PN designated — Part 1: Steel flanges
EN 12982, Industrial valves — End-to-end and centre-to-end dimensions for butt welding end valves
EN 1515-1:1999, Flanges and their joints — Bolting — Part 1: Selection of bolting
ASME B1.1, Unified Inch Screw Threads UN and UNR Thread Form
ASME B1.20.1, Pipe Threads, General Purpose (Inch)
ASME B16.5, Pipe Flanges and Flanged Fittings
ASME B16.10, Face to Face and End to End Dimensions of Valves
ASME B16.34:2004, Valves Flanged, Threaded and Welding End
ASME B18.2.2, Square and Hex Nuts
MSS-SP-55, Quality Standard for Steel Castings for Valves, Flanges and Fittings and Other Piping
2)
Components — Visual Method for Evaluation of Surface Irregularities
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
service pressure/temperature rating
lesser of the shell or seat pressure/temperature rating
2) Manufacturers Standradization Society standard.
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ISO 7121:2006(E)
3.2
anti-static design
design that provides for electrical continuity between the body, ball and stem of the valve
3.3
anti-blow-out design
design that ensures the valve stem cannot be ejected from the body in the event of the gland being removed
while the valve is under pressure
4 Pressure/temperature ratings
4.1 Valve rating
The service pressure/temperature rating applicable to valves specified in this International Standard shall be
the lesser of the shell rating, 4.2 or the seat rating, 4.3.
4.2 Shell rating
4.2.1 The pressure/temperature ratings applicable to the valve pressure containing shell (the pressure
boundary elements, e.g. body, body cap, trunnion cap, cover, body inserts) shall be in accordance with that
specified in the pressure/temperature tables of either ASME B16.34, Standard Class, for Class designated
valves, or EN 1092-1 for PN designated valves.
4.2.2 The temperature for a corresponding shell pressure rating is the maximum temperature that is
permitted for the pressure-containing shell of the valve. In general, this maximum temperature is that of the
contained fluid. The use of a pressure rating corresponding to a temperature other than that of the contained
fluid is the responsibility of the user. For temperatures below the lowest temperature listed in the
pressure/temperature tables (see 4.2.1), the service pressure shall be no greater than the pressure for the
lowest listed temperature. Consideration should be given to the loss of ductility and impact strength of many
materials at low temperature.
4.3 Seat and seal rating
4.3.1 Non-metallic elements, e.g. seat, seals or stem seals can impose restrictions on the applied
pressure/temperature rating. Any such restriction shall be shown on the valve identification plate in
accordance with 7.4.
4.3.2 The design shall be such that, when either polytetrafluoroethylene (PTFE) or reinforced PTFE is used
for seats, the minimum valve pressure/temperature rating shall be as specified in Table 1. Designs using
these seating materials having pressure/temperature ratings less than those shown in Table 1 are not in
compliance with this International Standard.
4.3.3 Seat ratings for other seat materials shall be the manufacturer’s standard. However, the assigned
valve service pressure/temperature rating shall not exceed that of the valve shell.
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ISO 7121:2006(E)
Table 1 — Minimum seat pressure/temperature rating
a a
PTFE seats Reinforced PTFE seats
c c
bar bar
b
Temperature
Floating ball Trunnion Floating ball Trunnion
°C
DN u 50 50 < DN u 100 DN > 100 DN > 50 DN u 50 50 < DN u 100 DN > 100
DN > 50
NPS u 2 2 < NPS u 4 NPS > 4 NPS > 2 NPS u 2 2 < NPS u 4 NPS > 4
NPS > 2
−29 to 38 69,0 51,0 19,7 51,0 75,9 51,0 19,7 51,0
50 63,6 47,1 18,2 47,1 70,4 47,8 18,4 47,8
75 53,3 39,2 15,2 39,2 59,9 40,4 15,6 40,4
100 43,0 31,3 12,1 31,3 49,4 33,1 12,8 33,1
125 32,7 23,3 9,1 23,3 38,9 25,8 10,0 25,8
150 22,4 15,4 6,1 15,4 28,3 18,4 7,2 18,4
175 12,1 7,5 3,0 7,5 17,8 11,1 4,4 11,1
200 — — — — 7,3 3,7 1,6 3,7
205 — — — — 5,2 2,3 1,0 2,3
For a given PN or Class designation, the assigned valve pressure/temperature ratings shall not exceed the shell ratings,
see 4.2.
a
Polytetrafluoroethylene seats.
b
Consult manufacturer for maximum design temperature rating of the valve seats.
c
5 2
1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .
5 Design
5.1 Flow passageway
The flow passageway includes the circular seat opening in the ball (the port) and the body runs leading
thereto. The body runs are the intervening elements that link the seat opening to the end connection, e.g. to
the thread end, weld end or socket end, or to the end-flange. Collectively, the flow passageway through the
ball port and body runs is referred to as the flow passageway. The ball port is categorized in this International
Standard as full-bore, reduced-bore, and double reduced-bore. The minimum effective diameter for each
category shall be such that a hypothetical cylinder, having a diameter according to Table 2, can be passed
through.
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ISO 7121:2006(E)
Table 2 — Cylindrical diameter for categorizing bore size
Minimum bore diameter
mm
Nominal
Reduced Double Nominal size
size Full bore
bore reduced bore
NPS
DN
PN 10, 16, 25 and 40 PN 63 PN 100 PN: all PN: all
Class 150 and 300 — Class 600 Class: all Class: all
8 6 6 6 6 N/A 1/4
10 9 9 9 6 N/A 3/8
15 11 11 11 8 N/A 1/2
20 17 17 17 11 N/A 3/4
25 23 23 23 17 14 1
32 30 30 30 23 18 11/4
40 37 37 37 27 23 11/2
50 49 49 49 36 30 2
65 62 62 62 49 41 21/2
80 74 74 74 55 49 3
100 98 98 98 74 62 4
150 148 148 148 98 74 6
200 198 196 194 144 100 8
250 245 245 241 186 151 10
300 295 293 291 227 202 12
350 325 322 318 266 230 14
400 375 371 365 305 250 16
450 430 423 421 335 305 18
500 475 467 453 375 335 20
N/A Valves having this configuration are not within the scope of this International Standard.
For Class 900, only valves having reduced port are within the scope of this International Standard.
5.2 Body
5.2.1 Body wall thickness
5.2.1.1 The minimum valve body wall thickness, t , shall be as specified in Table 3, except that for
m
butt-welding end valves the welding ends for connection to pipe shall be in accordance with the requirements
of Figure 1.
5.2.1.2 The minimum thickness requirements are applicable to, and are measured from, internally wetted
surfaces, i.e. up to the point where body seals are effective.
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ISO 7121:2006(E)
Table 3 — Valve body wall thickness
PN 10 and 16 25 and 40 63 100 — PN
a
Class 150 300 — 600 900 Class
Minimum valve body wall thickness, t
m
Nom. mm Nom.
size size
Double Double Double Double
Full Reduced Full Reduced Full Reduced Full Reduced Reduced
DN NPS
reduced reduced reduced reduced
bore bore bore bore bore bore bore bore bore
bore bore bore bore
8 2,7 2,7 N/A 2,9 2,9 N/A 2,7 2,7 N/A 3,1 3,1 N/A 3,4 1/4
10 2,9 2,9 N/A 3,0 2,9 N/A 2,9 2,9 N/A 3,4 3,3 N/A 3,8 3/8
15 3,1 3,1 N/A 3,2 3,2 N/A 3,1 3,1 N/A 3,6 3,6 N/A 4,1 1/2
20 3,4 3,4 N/A 3,7 3,7 N/A 3,5 3,5 N/A 4,1 4,1 N/A 5,8 3/4
25 3,9 3,8 3,8 4,1 4,1 4,1 4,0 4,0 4,0 4,7 4,6 4,6 6,0 1
32 4,3 4,2 4,2 4,7 4,6 4,6 4,4 4,3 4,3 5,1 5,0 5,0 6,4 11/4
40 4,7 4,5 4,5 5,2 5,0 5,0 4,8 4,7 4,7 5,5 5,4 5,4 5,8 11/2
50 5,5 5,3 5,3 6,2 5,9 5,9 5,6 5,5 5,5 6,3 6,0 6,0 7,0 2
65 5,7 5,6 5,6 6,7 6,5 6,5 6,5 6,3 6,3 6,7 6,4 6,4 7,9 21/2
80 6 5,9 5,9 7,1 6,9 6,9 7,2 7,0 7,0 7,6 7,2 7,2 9,4 3
100 6,3 6,3 6,3 7,6 7,6 7,6 8,2 7,9 7,9 9,2 8,7 8,7 11,8 4
150 7,1 6,9 6,9 9,3 8,9 8,9 10,1 9,8 9,8 12,6 11,8 11,8 16,3 6
200 7,9 7,7 7,7 10,9 10,4 10,4 12,5 12,0 12,0 15,7 14,7 14,7 20,5 8
250 8,7 8,4 8,4 12,55 12,0 12,0 14,5 13,5 13,5 18,9 17,6 17,6 24,9 10
300 9,5 9,2 9,2 14,2 13,5 13,5 16,5 15,5 15,5 22,3 20,7 20,7 29,1 12
350 10 9,6 9,6 15,2 14,4 14,4 17,8 16,8 16,8 24,1 22,5 22,5 31,8 14
400 10,8 10,4 10,4 16,8 16 16 19,8 18,6 18,6 27,3 25,4 25,4 36,0 16
450 11,7 11,1 11,1 18,7 17,3 17,3 21,7 20,4 20,4 31,1 28,9 28,9 42,0 18
500 12,4 11,9 11,9 20,2 18,8 18,8 24,0 22,5 22,5 33,2 30,8 30,8 44,3 20
N/A Valves having this configuration are not within the scope of this International Standard.
a
For Class 900, only valves having reduced ball ports are within the scope of this International Standard.
5.2.1.3 Local areas having less than minimum wall thickness are acceptable, provided that all of the
following conditions are satisfied:
⎯ the area of sub-minimum thickness can be enclosed by a circle, the diameter of which is not greater than
0,35 dt , where d is the minimum bore diameter given in Table 2 and t is the minimum wall thickness
m
m
given in Table 3;
⎯ the measured thickness is not less than 0,75 t ;
m
⎯ enclosed circles are separated from each other by an edge to edge distance of not less than 1, 75 dt .
m
5.2.1.4 The manufacturer, taking into account such factors as component bolting or thread assembly
loads, rigidity needed for component alignment, other valve design details and the specified operating
conditions, is responsible for determining if a larger wall thickness is required.
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ISO 7121:2006(E)
Dimensions and tolerances in millimetres
a) Welding end for connection to pipe of wall thickness T u 22 mm
b) Welding end for connection to pipe of wall thickness T > 22 mm
Key
A nominal outside diameter of welding end (see Table 4)
B nominal inside diameter of pipe (see Table 4 for applicable tolerance)
T nominal wall thickness of pipe
The inside and outside surfaces of valve welding ends are machine finished overall. The contour outside the envelope
formed by the end of the welding end and the dimension 1,5 T is at the option of the manufacturer, unless specifically
ordered otherwise.
Intersections should be slightly rounded.
Valves with minimum wall thickness equal to 3 mm or less may have ends cut square or slightly chamfered.
For nominal outside diameters and wall thickness of standard steel pipe, see ISO 4200 or ASME B36.10.
Figure 1 — Welding ends
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ISO 7121:2006(E)
Table 4 — Welding ends
Nominal size, DN 15 20 25 32 40 50 65 80 100 150 200 250 300 350 400 450 500
Nominal size, NPS 1/2 3/4 1 11/4 11/2 2 21/2 3 4 6 8 10 12 14 16 18 20
diameter 22 28 35 44 50 62 78 91 117 172 223 278 329 362 413 464 516
A, mm
+2,5
+4
tolerance
−1,0
−1
+1 +2 +3
B, mm tolerance
−1 −2 −2
5.2.2 Flanged ends
5.2.2.1 Body end flanges shall comply with the requirements of ASME B16.5 for Class designated valves
and EN 1092-1 for PN designated valves. Raised face end flanges shall be provided, unless otherwise
specified by the purchaser.
5.2.2.2 Face-to-face dimensions for flanged-end valves shall be in accordance with ASME B16.10 for
Class designated valves or ISO 5752:1982, Basic Series 1, 14, and 27, for PN designated valves, with an
applicable tolerance for DN u 250 of ± 2 mm and for DN W 300 of ± 4 mm.
5.2.2.3 End flanges shall be either cast or forged integral with the body or end piece of a split body
design, or attached by welding by a qualified welder using an accepted welding procedure, with the condition
that all such flanges on valves larger than DN 50 shall be butt-welded. Any heat treatment necessary to
ensure that the material is suitable for the full range of service temperature shall be performed.
5.2.2.4 End flange facing finish shall be in accordance with ASME B16.5 for Class designated valves or
EN 1092-1 for PN designated valves unless otherwise specified by the purchaser.
5.2.3 Butt-welding ends
5.2.3.1 Butt-welding ends shall be in accordance with Figure 1 and Table 4, unless otherwise specified
by the purchaser.
5.2.3.2 End-to-end dimensions for Class designated valves shall be in accordance with ASME B16.10 for
either the long or short pattern, or in accordance with EN 12982 for PN designated valves.
5.2.4 Socket welding ends
5.2.4.1 The socket bore axis shall coincide with the end entry axis. Socket end faces shall be
perpendicular to the socket bore axis. The socket bore diameter and its depth shall be as specified in Table 5.
5.2.4.2 The minimum socket wall thickness, extending over the full socket depth shall be as specified in
Table 6.
5.2.4.3 End to end dimensions for socket welding end valves shall be established by the manufacturer.
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ISO 7121:2006(E)
Table 5 — Socket diameter and depth
a b
Diameter Depth
DN NPS
mm
8 14,1 9,5 1/4
10 17,5 9,5 3/8
15 21,7 10 1/2
20 27,0 13 3/4
25 33,8 13 1
32 42,5 13 11/4
40 48,6 13 11/2
50 61,1 16 2
65 73,8 16 21/2
80 89,7 16 3
100 115,1 19 4
a
The applicable diametral tolerance is
+0,5
⎯ for DN u 50, and
0
+0,7
⎯ for DN > 50.
0
b
The depth dimension is a minimum value.
5.2.5 Threaded ends
5.2.5.1 The threaded end thread axis shall coincide with the end entry axis. The minimum wall thickness
at the threaded end shall be as specified in Table 6. An approximate 45° lead-in chamfer, having an
approximate depth of one-half the thread pitch, shall be applied at each threaded end.
5.2.5.2 The end threads shall be either taper or parallel pipe threads meeting the applicable requirements
of ISO 7-1, ISO 228-1 or ASME B1.20.1, with threads gauged in accordance with ISO 7-2, ISO 228-2 or
ASME B1.20.1, as applicable. The required pipe thread shall be specified in the purchase order.
5.2.5.3 End-to-end dimensions for threaded end valves shall be established by the manufacturer.
5.2.6 Body openings
Trunnion mounted valves that employ upstream sealing seats shall be fitted with a test plug, DN 15 (NPS 1/2)
or smaller, having threads in accordance with 5.2.5.2 in order to complete the closure tightness test. Other
tapped openings, for any purpose, are permitted only when specified by the purchaser.
5.2.7 Anti-static design
When specified in the purchase order, valves shall incorporate an antistatic feature that ensures electrical
continuity between stem and body of valves DN u 50 and between ball, stem and body of larger valves. The
antistatic feature shall have electrical continuity across the discharge path with a resistance not exceeding
10 Ω from a power source not exceeding 12 V d.c. when type tested on a new, dry, as-built valve after
pressure testing and cycling of the valve at least five times.
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ISO 7121:2006(E)
Table 6 — Socket and threaded end wall thickness
PN 10, 16, 25 and 40 63 and 100 — PN
Class 150 and 300 600 900 Class
Minimum wall thickness
DN NPS
mm
8 3,0 3,3 4,1 1/4
10 3,0 3,6 4,3 3/8
15 3,3 4,1 5,3 1/2
20 3,6 4,3 6,1 3/4
25 3,8 5,1 6,9 1
32 3,8 5,3 7,1 11/4
40 4,1 5,6 7,9 11/2
50 4,6 6,1 9,7 2
65 5,6 7,6 10,4 21/2
80 6,4 8,6 12,2 3
100 7,5 10,1 14,3 4
5.2.8 Anti-blow-out stem
The valve design shall be such that the stem seal retaining device is not the sole means used to retain the
stem. The design shall ensure that, while under pressure, the stem is not ejected from the valve by the
disassembly of valve external parts, e.g. gland and gland flange bolting. See Annex B.
5.2.9 Ball-stem construction
5.2.9.1 The valve design shall be such that if a failure occurs either between the stem-to-ball connection
or any part of the stem within the pressure boundary, no portion of the stem is ejected when the valve is under
pressure.
5.2.9.2 Both the stem-to-ball connection and all of that part of the stem within the pressure boundary
shall be designed to exceed the torsional strength of the stem external to the packing.
5.2.9.3 The stem and the connection between the stem and the ball shall be designed to preclude
permanent deformation or failure of any part when a force applied to the direct operating lever or the
operational means of a manual gear operator, whichever is furnished with the valve, transmits a torque to the
valve stem equal to twice the manufacturer’s maximum recommended torque.
5.2.9.4 The manufacturer’s recommended torque shall be based on clean and non-lubricated liquids with
a viscosity not higher than water at a differential pressure equal to the maximum differential service pressure.
5.2.10 Ball construction
The ball shall have a circular bore (flow passageway).
5.2.11 Operating means
5.2.11.1 Valves that are solely manually operated, i.e. without an attached gear or power-assist device,
shall be fitted with lever-type handles unless otherwise specified by the purchaser.
5.2.11.2 Gear operators, when specified or required to meet the operating force requirements of 5.2.11.3,
shall be provided with handwheels for actuation.
10
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